问题
While writing data to cassandra from spark, data is not getting written.
The flash back is:
I am doing a kafka-sparkStreaming-cassandra integration.
I am reading kafka messages and trying to put it in a cassandra table CREATE TABLE TEST_TABLE(key INT PRIMARY KEY, value TEXT).
kafka to spark-streaming is running cool, but spark to cassandra, there is some issue...data not getting written to table.
I am able to create a connection with cassandra, but the data is not getting inserted into the cassandra table. The output shows its getting connected and the next second getting disconnected.
The strings for System.out.print() is all at the output.
+++++++++++cassandra connector created++++++++++++++++++++++++++++
+++++++++++++streaming Connection done!+++++++++++++++++++++++++++
++++++++++++++++JavaDStream<TestTable> created++++++++++++++++++++++++++++
Cassandra shell shows 0 rows.
the full code and the logs and dependencies are below:
public class SparkStream {
static int key=0;
public static void main(String args[]) throws Exception
{
if(args.length != 3)
{
System.out.println("parameters not given properly");
System.exit(1);
}
Logger.getLogger("org").setLevel(Level.OFF);
Logger.getLogger("akka").setLevel(Level.OFF);
Map<String,Integer> topicMap = new HashMap<String,Integer>();
String[] topic = args[2].split(",");
for(String t: topic)
{
topicMap.put(t, new Integer(3));
}
/* Connection to Spark */
SparkConf conf = new SparkConf();
conf.set("spark.cassandra.connection.host", "localhost");
JavaSparkContext sc = new JavaSparkContext("local[4]", "SparkStream",conf);
JavaStreamingContext jssc = new JavaStreamingContext(sc, new Duration(5000));
/* connection to cassandra */
CassandraConnector connector = CassandraConnector.apply(sc.getConf());
System.out.println("+++++++++++cassandra connector created++++++++++++++++++++++++++++");
/* Receive Kafka streaming inputs */
JavaPairReceiverInputDStream<String, String> messages = KafkaUtils.createStream(jssc, args[0], args[1], topicMap );
System.out.println("+++++++++++++streaming Connection done!+++++++++++++++++++++++++++");
/* Create DStream */
JavaDStream<TestTable> data = messages.map(new Function< Tuple2<String,String>, TestTable >()
{
public TestTable call(Tuple2<String, String> message)
{
return new TestTable(new Integer(++key), message._2() );
}
}
);
System.out.println("++++++++++++++++JavaDStream<TestTable> created++++++++++++++++++++++++++++");
/* Write to cassandra */
javaFunctions(data).writerBuilder("testkeyspace", "test_table", mapToRow(TestTable.class)).saveToCassandra();
jssc.start();
jssc.awaitTermination();
}
}
class TestTable implements Serializable
{
Integer key;
String value;
public TestTable() {}
public TestTable(Integer k, String v)
{
key=k;
value=v;
}
public Integer getKey(){
return key;
}
public void setKey(Integer k){
key=k;
}
public String getValue(){
return value;
}
public void setValue(String v){
value=v;
}
public String toString(){
return MessageFormat.format("TestTable'{'key={0}, value={1}'}'", key, value);
}
}
The log is:
+++++++++++cassandra connector created++++++++++++++++++++++++++++
+++++++++++++streaming Connection done!+++++++++++++++++++++++++++
++++++++++++++++JavaDStream<TestTable> created++++++++++++++++++++++++++++
14/12/09 12:07:33 INFO core.Cluster: New Cassandra host localhost/127.0.0.1:9042 added
14/12/09 12:07:33 INFO cql.CassandraConnector: Connected to Cassandra cluster: Test Cluster
14/12/09 12:07:33 INFO cql.LocalNodeFirstLoadBalancingPolicy: Adding host 127.0.0.1 (datacenter1)
14/12/09 12:07:33 INFO cql.LocalNodeFirstLoadBalancingPolicy: Adding host 127.0.0.1 (datacenter1)
14/12/09 12:07:34 INFO cql.CassandraConnector: Disconnected from Cassandra cluster: Test Cluster
14/12/09 12:07:45 INFO core.Cluster: New Cassandra host localhost/127.0.0.1:9042 added
14/12/09 12:07:45 INFO cql.CassandraConnector: Connected to Cassandra cluster: Test Cluster
14/12/09 12:07:45 INFO cql.LocalNodeFirstLoadBalancingPolicy: Adding host 127.0.0.1 (datacenter1)
14/12/09 12:07:45 INFO cql.LocalNodeFirstLoadBalancingPolicy: Adding host 127.0.0.1 (datacenter1)
14/12/09 12:07:46 INFO cql.CassandraConnector: Disconnected from Cassandra cluster: Test Cluster
The POM.xml dependencies are:
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming-kafka_2.10</artifactId>
<version>1.1.0</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-streaming_2.10</artifactId>
<version>1.1.0</version>
</dependency>
<dependency>
<groupId>com.datastax.spark</groupId>
<artifactId>spark-cassandra-connector_2.10</artifactId>
<version>1.1.0</version>
</dependency>
<dependency>
<groupId>com.datastax.spark</groupId>
<artifactId>spark-cassandra-connector-java_2.10</artifactId>
<version>1.1.0</version>
</dependency>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.10</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<groupId>com.msiops.footing</groupId>
<artifactId>footing-tuple</artifactId>
<version>0.2</version>
</dependency>
<dependency>
<groupId>com.datastax.cassandra</groupId>
<artifactId>cassandra-driver-core</artifactId>
<version>2.1.3</version>
</dependency>
is there something wrong with the code? or cassandra configuration?
回答1:
solved the issue. the columnMapper wasnt able to access the getters and setters of class TestTable. So changed the access modifier to public. but now i had 2 public classes in one file. which is an error. so created another java file TestTable.java with class as
public class TestTable implements Serializable {
//code
}
now the messages are being read from kafka and getting stored in cassandra table
来源：https://stackoverflow.com/questions/27386223/kafka-spark-streaming-data-not-getting-written-into-cassandra-zero-rows-inserte